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FCC Bars Lightsquared From Using Airwaves
New submitter mc6809e writes with news that Lightsquared might have just been killed. From the article: "A proposed wireless broadband network that would provide voice and Internet service using airwaves once reserved for satellite-telephone transmissions should be shelved because it interferes with GPS technology, the Federal Communications Commission said Tuesday. The news appears to squash the near-term hopes for the network pushed by LightSquared, a Virginia company that is majority-owned by Philip Falcone, a New York hedge fund manager."
LightSquared, naturally, continues to deny that the interference is real.
The FCC made a good and wise decision in this situation.
It is unrealistic to expect the desires of a company which wants
only to make money should override the safety of a public
which depends increasingly on GPS.
Really, the FCC and/or the GPS equipment manufacturer should be the ones being penalised.
As a practical matter, there's no way to do that. If you allow Lightspeed to operate, you penalize the USERS of the (allegedly) badly designed GPS devices. It does suck to be Lightspeed, because GPS really is much more important than them.
The key sequence to access my Slashdot bookmark in Firefox is Alt-B-S. I don't believe this is a coincidence.
The last time /. discussed this, it was pointed out that the spectrum L^2 was aiming for was intended for low-power satellite signals and was never intended to be used for (relatively) powerful ground stations. They were essentially trying to buy spectrum on-the-cheap and then repurpose it in a way that was virtually guaranteed to interfere with adjacent spectrum. So, while GPS devices could certainly be better-designed, this was more an incident of L^2 trying to abuse the system.
Physics, alas, makes for a harsh mistress.
I wish I had a kryptonite cross, because then you could keep Dracula and Superman away.
I mean if it gives you broadband, voice and blocks GPS guided missiles, what more could you want?
It's my understanding* that Lightsquared's equipment was never the issue, but rather the GPS equipment that got interference were just poorly designed. If the GPS equipment was held to the standards it should have been, Lightsquared's equipment wouldn't have interfered. Yet Lightsquared are the ones being shafted, simply because GPS is "too important".
That's not quite true. LS basically bought up a *satellite* band and tried to repurpose it for ground communications. It was then discovered that doing this caused some GPS equipment to malfunction. Whether or not you consider this GPS equipment to be "poorly designed", the fact remains that it was working absolutely fine for decades and LS's attempts to repurpose the ajacent band causes it to stop working. Expecting millions of GPS users to upgrade their GPS receivers just because LS wants to repurpose an existing band for a new use is ridiculous. On the other hand, if LS wants to buy shiny new GPS receivers for all these end-users...
So no, LS isn't "being shafted" - they purchased a satellite band with the intention of using it for ground communications, rather than its existing use, badgered the FCC into letting them repurpose it and then cried when it was found that this repurposing wasn't compatable with millions of existing devices.
http://blog.nexusuk.org
GPS receivers (and the filters in their electronics) were built with the assumption that neighboring frequencies would be used by other space-to-ground uses, and thus would have comparable signal strengths (that is, very low).
Having ground-based stations blasting out signals that are brazillions of times more powerful than the weak space-to-ground signals on adjacent frequencies would overwhelm the relatively weak signal from GPS. Filters that can allow the weak GPS signals through while blocking out the immensely more powerful signals on neighboring frequencies would be bulky and expensive. Devices not equipped with those specialized filters (that is, essentially every GPS receiver ever made) would be screwed.
I'm sure that if LightSquared wanted to use the frequencies they acquired for space-to-ground uses, the FCC would have very little trouble with it and the potential for interference with GPS would be essentially nil. Instead, LightSquared purchased (leased? I'm nowhere near an expert on this kind of thing.) these frequencies at a cheap price due to their being intended for space-to-ground use and was trying to change their classification to use them for ground-based transmitters (thus saving LightSquared tons of money acquiring spectrum). They gambled big and (rightfully) lost.
Reliable GPS service is more important than the communication network LightSquared proposed, particularly in regards to safe navigation for aircraft and vessels.
Not quite. The spectrum adjacent to GPS frequencies was authorized for for use with other satellite services, which obviously have a very low signal level. GPS receivers were designed with that in mind. That's not unreasonable, in the real world there's no such thing as a perfect filter with vertical skirts.
Lightsquared "bought" this spectrum, much cheaper than similar spectrum allocated for terrestrial use. They then fast tracked a petition through the FCC to get authorized to use that spectrum terrestrially. The problem is, that produces much stronger signals than GPS receivers were designed to deal with.
If Lightsquared were to use the spectrum as originally intended, there would be no issue. Instead, they want to have their cake, and eat it too, by paying for relatively low cost satellite spectrum, but using it for terrestrial transmitters.
"National Security is the chief cause of national insecurity." - Celine's First Law
Actually, the spectrum was never intended for terrestrial use at all. Lightsquared applied for an exemption to apply the spectrum for terrestrial use, but they had to prove that it did not intefere with GPS. Most RF engineers would have told you that they where doomed from the start to fail, as the physics does not allow you to do this. All RF equipment have to contend with a thing call adjacent channel rejection - i.e. whilst tuned to its own channel a device must reject inteference from channels adjacent to its own by using a bandpass filter. Bandpass filters are not perfect (i.e. it is not a brickwall) and some interference always leaks through. The specific issue here is that the terrestrial signal would have been so large compared to the signal received from the GPS sattelite that the bandpass filters would have been unable to suppress the signal in the adjacent channel. This is akin to someone shouting in your ear, while you are trying to listing to someone whispering 20meters away.
A picture is worth exactly 1024 words.
"A proposed wireless broadband network that would provide voice and Internet service using airwaves once reserved for satellite-telephone transmissions should be shelved because it interferes with GPS technology, the Federal Communications Commission said Tuesday
That's a massive simplification. They sell mobile satellite internet, and have done so for a long time, and will do so into the indeterminate future, this has nothing to do with that.
The LS idea was to provide a backend carrier to local on ground cellular providers for internet traffic. Same as your off the shelf 3G service you now "enjoy" but instead of your greedy provider paying AT&T (or whoever) for fiber to the cell phone tower, they'd use the satellite service.
Except... they didn't have an allocation for their ground network. Hmm. What if we reuse the satellite freqs, yeah that'll work. Well, except that the would ruin/destroy/eliminate the possibility of anyone on the ground hearing the satellites without a huge dish or technically impossible filtering. OK no problemo we'll dump all our satellite customers and focus on the ground guys, and use the marketing for satellite "as if" we're not a ground 3G provider. Whoops that'll kill all the adjacent satellite services too. Oh Oh, GPS is adjacent.
Well, so much for that bad idea.
Note there is no reason that instead of paying AT&T for fiber to a cell tower in the middle of nowhere, LS can't provide slow and high latency service RIGHT NOW to that cell tower... this FCC bar only stops them from setting up their own tower and using the satellite freqs to set up something like a 3G service.
The standard /. car analogy is this is kind of like getting rid of the SUV exception where hyper obese ultra low MPG passenger cars are permitted under the legal fiction they are classified as trucks not cars. That takes care of the analogy "why the F are they installing 100 watt ground transmitters on an allocation for satellite transmitters only?". Or maybe a better analogy is LS thought it would be fun to build a network of hydrogen fueling stations, and figured no one would have any problem if they used an off the shelf gasoline filling nozzle instead of a technically correct solution that would not result in an infinite number of burnout fires. That takes care of the analogy "why the F are they installing 100 watt ground transmitters right next to satellite receivers and even daydreaming that won't knock out the receivers".
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
This has been coming up over on Ars Technica for awhile now and the explanation isn't so much that the GPS equipment is poorly designed but rather that Lighsquared is trying to use the spectrum in a way that it was not licensed to do so in. In short, the spectrum that they licensed is for low power satellite communications (i.e. GPS) and they want to use the same spectrum but to increase the power at which they broadcast it up to normal terrestrial levels. At that point the common analogy is that it is like trying to tell the color of a flashlight from a couple miles away: once you spot it you can tell when the color changes, but if someone comes along and places a high power search light next to it, the flashlight will drown out by the power of the other light source.
Also, don't forget that radio signals aren't prefect pathways either and you can be broadcasting on one frequency and have it bleed over into another frequency. This is why radio stations and television channels are allocated in such a way that they aren't directly next to each other (think radio channel 100 and 100.1).
So in summary, this isn't an equipment problem but a physics problem: making the equipment better isn't going to help the fact that the signal would be drown out if Lighsquared were to broadcast on a satellite channel at terrestrial power levels.
The article seems to gloss over the most critical point that breaks this deal, painting LightSquared as a victim in the process:
LightSquared's spectrum (which was bought from another company) was for SATELLITE transmissions, not TERRESTRIAL.
Satellite spectrums are much cheaper, but can't be used for terrestrial transmissions.
LightSquared is in fact trying to cheap out by using a cheaper spectrum.
Analogy:
LightSquared tried to buy a plot of cheap residential land to start a chemical/manufacturing plant, which affects nearby residents.
They should have bought a piece of commercial land that supports their requirements.
More technically:
Satellite signals are weak as they are sent from huge distances from satellites with limited power. To receive these signals, the receivers must be tuned to be sensitive to these signals. If LightSquare were to transmit terrestrially from the bordering spectrum (to pass through walls and what-have-you), the transmitted strength will be thousands of times stronger than the GPS signals, invariably causing interference with GPS signals. Even if GPSes are built with a filter (which they shouldn't need to, the nearby spectrums should also be weak signals!), it would be prohibitively expensive/unfeasible to filter the strong terrestrial signals.
> you penalize the USERS of the (allegedly) badly designed GPS devices
I maintain a 50,000 watt AM and two 100,000 watt FMs, and we get interference complaints all the time. The only fair rule for EVERYONE involved is to say, "as long as I'm following the terms of my license, and I'm SURE that my transmitter isn't putting out unwanted products, there's nothing I can do."
I'm friendly; I offer tips and suggest filters; I help if I can. But there's really not much I can do if they have a cheap radio. Am I "penalizing" them for buying a $20 table radio from WalMart? I don't think so.
You say "allegedly," but believe me, some of the cheap Chinese junk (albeit with good-sounding American brand names) being sold now isn't worth the money to crush and melt it. I would be astonished if the same isn't true of GPS equipment.
Cogito, igitur comedam pizza.
One wonders if Lightsquared thought that they had a good chance of pulling this off, either through technological optimism or confidence in their legal team(For whatever reason "Rural broadband!!!" appears to be the FCC's root password) or if this was some sort of long-odds/high-rewards gamble by the hedge fund chap...
On the one hand, being able to convert a swath of satellite-to-ground spectrum into ground-ground spectrum would be crazy valuable, and likely result in some very nice returns. On the other, trying to go up against the now-firmly-entrenched users of GPS(ie. almost everybody) is a risky move indeed.
Did they miscalculate the odds, or were they happy to take very bad odds for the possibility of extremely high returns?
it's more like getting a permit to open a bar next door to an observatory but the city strictly requires you to keep your outdoor lighting to a minimum so as not to disturb the telescope next door. yet you still put up a huge neon sign and searchlight and when the observatory complains that your light pollution has ruined its ability to gather data, you say 'it's not my fault your telescope sucks'.
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Is this the MPAA? Is this the RIAA? Is this the DMCA? I thought it was the USA!
Wow. You couldn't be more confused. Analog TV operated in 54-88 MHz, 174-216 MHz (VHF), and 470-890 MHz (UHF) bands. GPS is up above 1 GHz, 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal) being the primary signals. The frequencies that Lightsquared wants to use have nothing to do with the any spectrum which was previously used for TV.
"National Security is the chief cause of national insecurity." - Celine's First Law
According to the actual 2003 decision by the FCC:
Today we decide to permit flexibility in the delivery of communications by Mobile Satellite Service (MSS) providers [cut]. Specifically, we permit MSS licensees to integrate ancillary terrestrial components (ATCs) into their MSS networks
...
We will authorize MSS ATC subject to conditions that ensure that the added terrestrial component remains ancillary to the principal MSS offering. We do not intend, nor will we permit, the terrestrial component to become a stand-alone service.
That is, the decision was to let those offering mobile satellite services the ability to enhance their networks. This guy wanted to create a stand-alone cell phone network, which was explicitly not permitted in the 2003 decision.
The GPS units are not faulty. The spectrum they use are reserved for SATELLITE reception, not terrestrial broadcast. The signal levels received are so incredibly weak, that it is quite difficult, certainly not cheap, to build filters to filter out a nearby signal that is several order of magnitude stronger than yours. The spectrum was reserved, by the FCC, such that the neighboring spectrum would be like weak signals, which makes building receivers with high sensitivity possible and affordable.
I am sorry, but it was lightspeed who deceptively came in, got the spectrum, then changed from a mostly satellite based service (which would have been fine in that spectrum), to one consisting of tens of thousands of TERRESTRIAL transmitters in the L1 band, that simply overpower the nearby satellite downlink signals.
You just cannot build a high sensitivity receiver with a filter strong enough to filter out that kind of interference.
The FCC never should have granted them a go ahead in that frequency band in the first place.
Let's be clear - the FCC is not in the business of validating that any particular device is generally well-made or robustly-designed. Their one and only concern wrt to type acceptance is the RF _emissions_ of the device. They do not require testing of receivers for susceptibility to nearby carriers, intermodulation, desense or anything else, only their (in the case of a receiver, unintentional-) emissions. All not-otherwise licensed equipment carries the all-too familiar Part 15 warning about not causing and having to accept interference.
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
Let's rewind back to the year 2000.
You're a hardware engineer. You've been tasked with building a GPS front end in a cost-effective manner.
You decide to do your homework. You look up the FCC regulations for adjacent frequency bands. Since very high power terrestrial transmissions were prohibited by federal law (i.e. punishable by pound-me-in-the-ass federal prison time for violations), you run the calculations and decide how many -dB/octave your front-end filter needs to exclude signals that you could expect in real world applications.
Sure, you could have gone with a filter that had 2x or 3x steeper roll-off. But why? Your manager asked you to do this in a cost-effective manner, and it's patently illegal for such strong signals to exist.
So you're telling me that a hardware engineer who does his homework and designs a filter that can remove signals which are the maximum legal power is "shoddy"?
:(){
I would also point out that the frequency band GPS and satellite signals are in are much cheaper than terrestrial frequencies. As such, Lightspeed abused a (poorly conceived) FCC ruling for filling in poor reception areas with local ground based transmitters, to take cheap satellite spectrum, and repurpose it for a very large and high-powered terrestrial network, without paying similar licensing fees other terrestrial providers have to pay for their spectrum.
The whole loophole started by the FCC allowing ground based transmitters in the L1 band, but the intent was to supplement poor reception of satellite signals with some ground based ones. They never intended it to be repurposed for massive scale and high powered ground transmitters everywhere.
The laws of physics don't work well with you here when you have very weak signals from space competing with local, very strong signals on the ground, and only a few MHz apart in the GHz range. That was the original reason satellite based signals have their OWN spectrum. While it stinks for Lightspeed, they should know they never should have really gotten that spectrum from the FCC in the first place. The FCC dropped the ball on this one, but perhaps that's not too surprising how much corporations can buy influence in Washington these days.
And what if someone decided to operate a station on an adjacent frequency channel, with 10 megawatts of power? Or even half a channel over? (Rules? What rules? We just want a little variance in the rules!) Then suddenly people trying to receive your station get interference because the channel separation rules weren't designed for that kind of power on adjacent channels? The problem isn't "badly designed GPS devices", it's that this is a band which was allocated specifically for the purpose of satellite communication, which is by its very nature rather low-powered to begin with.
I'm almost surprised it took this long, except I'm sure there has been some ohbummer-related political interference going on behind the scenes. And it's probably still going on even now.
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
Does it appear to anyone else that at least half the Lightspeed defenders must be paid shills for the company? Think about it -- GPS has been around for 20+ years and is considered a utility now, the facts of Lightspeed's purchase of the spectrum (only intended for satellite use) are not in question, and neither is the physics of humongously strong signals next to a band where the signals are below the noise floor. And, who gets all excited about some company's spectrum license unless have a vested interest -- it's not usually of much general interest. I'd like to be proved wrong so I can continue to trust he integrity of sites like /. but I'd say , "Reader beware".
so it becomes a competitive question here - why aren't GPS devices better designed?
Because they were engineered with the constraints of their band in mind. If the rules of the band are such that you don't need to worry about a powerful signal on an adjacent frequency, designing a filter to deal with such an adjacent signal is unnecessary expense.
GPS was around way before LightSquared's current plan.
Lightsquared doesn't want to set up a new SatPhone service. They want to use their satellite spectrum for ground-to-ground stations instead. GPS was using their own satellite spectrum LONG before LS decided they wanted to use adjacent spectrum for vastly more powerful (read: interfering) ground service. If all LightSquared wanted to do was set up a SatPhone service, then we would quite correctly be heaping scorn on cheap GPS makers...
It's not "shitty design" when a GPS cannot block out a tidal wave of signal from an adjacent band, when that band was only supposed to contain a garden-hose sized signal. Yes, equipment must "accept any interference", but not if that interference vastly more powerful than the spectrum was originally supposed to deal with.
Don't forget that in response to LightSquared, DirectTV and pretty much every single company that owns satellite to ground spectrum was filing for similar waivers essentially re-purposing satellite communications to ground-base communications and creating the potential for satellite apocalypse as it becomes thousands of times harder to communicate with *all* satellites, effecting weather, hurricane, tsunami forecasting, early warning systems, satTV and radio, etc, etc. GPS/LightSquared was the proxy war for all of these other providers and it's very, very good that LightSquared did not win.
And that's where the debate lies. LightSquared's license permits them two uses of the frequencies licensed:
LightSquared's argument is that they have met the second term of their license if they ensure that their earth-based transmitters do not leak out of their licensed bands, even if they interfere with licensed users of neighbouring bands; note that the FCC has been clear that one way to meet the second requirement is to replace receivers of the neighbouring bands with ones that cope with your interference, an option LS has rejected as impractical, as they cannot find affordable receivers that have both the GPS abilities of the receivers they're replacing and better rejection of LS's signals.
I appear to have a blog. Odd.
L2 made one big mistake. Stepping on a lot of toes? No biggie, happens all the time. Stepping on toes that are in a building with five sides? Might want to think about that.
What's the sense in building a receiver to reject adjacent channel interference that, via an FCC band plan, was never meant to exist? Managing the spectrum so that large amplitude signals are not present is a whale of a lot cheaper than turning a $100 GPS receiver into a $200 GPS receiver when the design and construction of the filtering necessary to reject the supposedly non-existent adjacent channel high power signal causes the doubling of the price.
If everyone just goes by the band plan, and doesn't try to do some end-run around the intent of the rules, then we can have $100 GPS receivers instead of $200 GPS receivers. I think building them cheaper is the better idea.
You understand radio a bit it seems. Here's what you're ignoring though, so follow me here: a high-precision GPS receiver must pick up signal at -165 dBm. This is right about at the noise floor. Its incredibly easy to cause interference with a receiver that must operate with these conditions, and incredibly difficult to design a filter that would actually be useful. You're talking about transmitters with 10^5 W output interfering with other transmitters in the same class. Its apples and oranges.
The rules upfront were clear; adjacent bands were for low power satellite use only.
The fact is that Lightsquared thought it could buy the influence to screw everybody else while getting richer. There is a reason the band they bought was so cheap.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
I'll bet you're not operating a terrestrial transmitter in a band that is restricted to satellite downlink are you? If you did, you would be shut down, and rightfully so.
The GPS gear was designed to operate adequately within the environment the FCC promised they would be in. LS begged the FCC to go back on that promise and was given every chance to demonstrate that it wouldn't cause a problem for any existing application. They failed to prove their case. End of story. Note that the FCC was under no obligation to even give them a chance to prove their case, they were entitled to just give them a flat NO.